Polarized electromagnetic device



Feb. 11, 1964 R. F. STEHLIK 3,121,194

POLARIZED ELECTROMAGNETIC DEVICE Filed March 1, 1960 2 Sheets-Sheet 1 IINVEN TOR. RUdO/ph F SfGh/I'k Feb. 11, 1964 R. F. STEHLIK 3,

POLARIZED ELECTROMAGNETIC DEVICE Filed March 1, 1960 2 Sheets-Sheet 2FIG. 312

26 I I 7 i I I I E I G 23 l IIJTM mm k A I I I I l J 22 FIG.2a

INVEN TOR. Rudolph F. Sfehl/lr Affy.

United States Patent 3,121,194 POLARIZED ELECTROMAGNETIC DEVICE RudolphFrank Stehlik, Antwerp, Belgium, assignor to Automatic ElectricLaboratories, Inc., Northlake, 111., a corporation of Delaware FiledMar. 1, 1960, Ser. No. 12,174 4 Claims. (Cl. 317171) The presentinvention relates to polarized electromagnetic structures or devices.Specifically the invention relates to a single coil alternating currentsignalling device or the like and more particularly concerns bellssuitable for use in telephone systems or similar situations. Theprincipal object of the invention is to provide a bell which can bemanufactured cheaply and in addition to being very light in weight,possesses compactness so that it can be installed in a convenientlysmall space.

In the past, a multitude of small parts were required to be assembled tomake up a compact alternating current signalling device. For instance,aside from the core and soft end iron pieces, separate armatures,hammers, hammer arms, pivot pins therefor, and bolts, rivets etc., allwent into making this assembly. A feature therefore of this invention isto provide a one piece integral ringer armature, hammer arm and hammercombined.

A second feature of this invention resides in the relationship of asingle coil and magnetic circuit to the abovementioned integral armaturehammer.

Other objects and features of this invention will become apparent from aperusal of the following specification taken in conjunction with theaccompanying drawings, of which:

FIG. 1 is a front view of a ringer structure embodying the features ofthis invention;

FIG. 2 is a front view of the one piece armature hammer and FIG. 2a is atop view thereof;

FIG. 3 is a top view of the mounting frame;

FIG. 3a is a view taken from the bottom of FIG. 3;

FIG. 3b is a view taken from the right side of FIG. 3;

FIG. 4 shows a top view of one of two polar plates;

FIGS. 5, 6 and 7 are schematic representations illustrating the fluxpaths set up by the permanent magnet and the electromagnet employed inthe ringer.

Referring to FIG. 1, the frame 30, constructed of brass or othersuitable non-magnetic material, is shown supporting the soft iron coilpole pieces 16, staked at four corners thereof. A ringer coil 14, woundon an iron core 10, having insulated spool heads 13, is disposed betweenthe coil pole pieces 16, and fastened thereto by the screws 12. Theframe 30 has a bent leg 32 perpendicular to the main portion thereoflying flush against the base plate 1. A hole 33 is provided in leg 32for insertion of a screw for fastening the frame 30 at one end to thebase 1. Also, a slotted hole 34 is provided through which a screw isinserted and screwed into a threaded hole (not shown) in base plate 1for adjustably securing the frame 30 to the base 1 at the opposite end.The particular form of the mounting frame 30 can be more clearlyascertained from FIGS. 3, 3a, and 3b. At the outer ends of frame 30 arefour lobes 38 for securing the pole pieces 16 within the apertureportion designated as 37. An opening designated as 39, is utilized tosecurely squeeze the legs 41 of two polarizing plates 40 between polepieces 16 and the frame 30. The form of the two polarizing plates can bemore clearly ascertained by the one shown in FIG. 4. As seen in FIG. 1there is a gap between the inner ends of the two polarizing plates 40 asthey lie horizontally. The notches 42 on the polar plates 40 permit theframe 30 to rest at a prescribed horizontal level in acocrdance withnotches on the pole pieces 16, whereby portions of legs 41 and portionsof pole pieces 16 pro trude upwardly through the apertures on the frame30.

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A cleft or opening 31 is utilized for insertion of a rectangularlyshaped permanent magnet 15 for resting on and bridging the gap betweenthe polar plates 40, and secured thereon by two inverted L-shaped ears36 of the frame 30 overlapping the top of the magnet. Spanning the upperends of the insulated terminal members 13 is a preferably brass or othernon-magnetizable flat spring 19, which tensions the polar plates 40 inan upward direction. The tension exerted by the spring 19 on the polarplates 40, further tend to stabilize the permanent magnet 15 within theears 36 and cleft 31.

Referring to FIGS. 2 and 2a, the combination armaturehammer comprises afiat armature portion 20, and along one edge rising perpendicular to theflat side, an elbow 22 forms the integral connection with the hammer arm21 which extends parallel to the flat surface of the armature. At theextreme end of hammer arm 21 is the hammer 23 lying between the twogongs 29 and 29' which are secured tothe base 1 by screws 28. Theelbow22 has a bearing pin hole 24 in alignment with a hole (not shown) in alobe 26 on armature 20, which holes lie in alignment between holes 37 onthe integral flanges 35 of frame 36 where a bearing pin 18 is insertablysecured by staking the ends of the pin within the holes 37'. Thus theone piece armature-hammer will pivot on hearing pin 18. Two indentations25 in armature-hammer 20 form openings above the inverted L-shaped ears36 of frame 30, to prevent engagement of the armature with these earsduring pivotal movement of the one piece armature-hammer while, at thesame time, keeping the air gap between the armature and the magnet at aminimum.

It should be appreciated that with the slotted hole 34, the entire unitcan be movably adjusted to place the hammer 23 at a point desiredbetween the gongs 29 and 29'. Furthermore, the screw holes in the gongsare off centered to further align the gongs in a desired location inrelation to the hammer 23, for a desirable hammer stroke adjustment.

Reference is now made to FIGS. 5, 6 and 7. In these figures thepermanent magnet, magnet core, polar plates and iron pieces are shown asintegral parts to simplify the schematic. The letters N and S indicatethe north and south poles respectively of the permanent magnet 15 (FIG.1). FIG. 5 shows the path of the permanent magnet flux when uninfiuencedby flux set up by the operating coil. FIG. 6 shows the path of thepolarizing flux and the flux set up by the operating coil during theapplication of one-half cycle of ringing current thereto and theresulting attraction on the armature. FIG. 7 shows the path of thepolarizing flux and the flux set up by the operating coil during theapplication of the second half of the same cycle of ringing currentthereto and the consequent actuation of the armature.

Thus, on the energization of the coil 14 by current in the properdirection the one-piece armature hammer is attracted to one of the polepieces and is pivotally moved in a first direction to cause hammer 23 tostrike gong 29, while with current in the reverse direction the armatureis attracted to the other pole pieces and the hammer 23 strikes the gong29. In this manner the alternate energization and de-energization of thecoil 14 produces the required ring.

From the foregoing it will be appreciated that a new ringing device hasbeen devised, which is economical to manufacture, is very compact,requires a minimum of parts and assemblance, requires very little spacefor mounting, and is comparatively light in weight.

What I claim and desire to secure by Letters Patent is:

1. In a telephone ringer, a core, an electromagnet wound on said core, apole piece of magnetic iron fixed to each end of said core and extendingat right angles thereto, a frame having openings at each end thereof andan opening in the center thereof, the extending ends of said pole piecesinserted through the openings in the ends of said frame so that theframe lies parallel to said core, a permanent magnet inserted in thecenter opening of said frame and magnetized in a direction at rightangles to the length of said core, a pair of L-shaped polar plates withthe short ends thereof lying parallel to said pole pieces and extendingthrough said end openings in said frame and the longer ends thereofextending toward each other between said core and said permanent magnetand forming an air gap between said longer ends, a bowed springextending between the ends of said core and bowed upward'to force saidlong ends of said L-shaped polar plates and said permanent magnetoutward from said core, and an armature pivoted at its center point tothe center of said frame and having its ends lying adjacent the ends ofsaid pole pieces, and a hammer arm-clapper integral with and extendingin a plane parallel with that of the said armature for striking thegongs of said ringer when the armature is vibrated.

2. In a telephone ringer having gongs and a clapper therefore, anoperating mechanism for vibrating the clapper comprising a core ofmagnetic iron having a winding thereon, a pair of pole pieces secured tothe ends of said core and extending upward at right angles therefrom, anarmature pivoted at its center point and having its outer ends lyingadjacent the ends of said pole pieces, a pair of L shaped pole pieceextensions having their short ends lying parallel to the outer ends ofsaid pole pieces and their longer ends extending toward each other in aplane parallel with the said core and armature and between the armatureand core and providing a short air gap between said longer ends, apermanent magnet, polarized in a direction at right angles to the lengthof the core and mounted between said air gap in the pole pieceextensions and the armature, a frame having a pair of bearings thereonupon which said armature is pivoted, and a tension spring for securingsaid pole pieces, said extensions and said permanent magnet to saidframe.

3. An electromagnetic structure comprising a core of magnetic materialhaving a wound bobbin thereon,

a pair of pole pieces extending at right angles from said core,

an armature,

a frame of non-magnetic sheet material etxending between said polepieces,

said frame having a center opening, an aperture portion at each end, apair of ears formed on said frame outwardly of said opening, and meansfor pivoting said armature at its center on said frame,

.a permanent magnet extending through said opening,

a pair of L-shaped members of magnetic material, the

long legs of said members extending from said pole pieces toward eachother in the space between said magnet and said bobbin, and the shortlegs of said members, as well as said pole pieces, extending throughsaid aperture portions and being fastened to said frame,

and a non-magnetic leaf spring pressing with its ends against saidbobbin and with its center against the long legs of said L-shapedmembers to urge said members against said magnet and said magnet againstsaid ears.

4. An electromagnetic structure as claimed in claim 3, whereinindentations are formed in said armature opposite said ears on saidframe to accommodate said ears and thereby provide minimum spacingbetween said armature and said magnet.

References Cited in the file of this patent UNITED STATES PATENTS2,547,537 Power Apr. 3, 1951 2,733,435 Bredenhoft Jan. 31, 19562,890,447 Lohs et al June 9, 1959 2,928,028 Persson Mar. 8, 19602,941,130 Fischer June 14, 1960 FOREIGN PATENTS 745,952 Great BritainMar. 7, 1956

1. IN A TELEPHONE RINGER, A CORE, AN ELECTROMAGNET WOUND ON SAID CORE, APOLE PIECE OF MAGNETIC IRON FIXED TO EACH END OF SAID CORE AND EXTENDINGAT RIGHT ANGLES THERETO, A FRAME HAVING OPENINGS AT EACH END THEREOF ANDAN OPENING IN THE CENTER THEREOF, THE EXTENDING ENDS OF SAID POLE PIECESINSERTED THROUGH THE OPENINGS IN THE ENDS OF SAID FRAME SO THAT THEFRAME LIES PARALLEL TO SAID CORE, A PERMANENT MAGNET INSERTED IN THECENTER OPENING OF SAID FRAME AND MAGNETIZED IN A DIRECTION AT RIGHTANGLES TO THE LENGTH OF SAID CORE, A PAIR OF L-SHAPED POLAR PLATES WITHTHE SHORT ENDS THEREOF LYING PARALLEL TO SAID POLE PIECES AND EXTENDINGTHROUGH SAID END OPENINGS IN SAID FRAME AND THE LONGER ENDS THEREOFEXTENDING TOWARD EACH OTHER BETWEEN SAID CORE AND SAID PERMANENT MAGNETAND FORMING AN AIR GAP BETWEEN SAID LONGER ENDS, A BOWED SPRINGEXTENDING BETWEEN THE ENDS OF SAID CORE AND BOWED UPWARD TO FORCE SAIDLONG ENDS OF SAID L-SHAPED POLAR PLATES AND SAID PERMANENT MAGNETOUTWARD FROM SAID CORE, AND AN ARMATURE PIVOTED AT ITS CENTER POINT TOTHE CENTER OF SAID FRAME AND HAVING ITS ENDS LYING ADJACENT THE ENDS OFSAID POLE PIECES, AND A HAMMER ARM-CLAPPER INTEGRAL WITH AND EXTENDINGIN A PLANE PARALLEL WITH THAT OF THE SAID ARMATURE FOR STRIKING THEGONGS OF SAID RINGER WHEN THE ARMATURE IS VIBRATED.